Patent GB-774340-A (GB)
Title: Improvements in or relating to lapping machines
IPC: B24B37/34
Filed: 1955-06-14
Abstract: 774,340. Lapping. CRANE PACKING CO. June 14, 1955 [June 18, 1954], No. 17123/55. Class 60 Workpieces are lapped by being fed over a stationary shelf 26, Fig. 1 into recesses in the periphery of a rotating plate 170 which carries them over the upper face of a rotating lap 14 and then discharges them at the shelf, the workpieces being arranged to enter successive recesses in the plate after passing through an opening in a state ionary ring 186; Figs. 1 and 3, which surrounds the plate and together with the recesses provides pockets for the workpieces. The lap 14 is supported above the upper face of a table structure 12 and as shown, cooperates with two rotating work plates 170 which are each surrounded with a stationary ring 186 and associated with a shelf 26; each plate 170 in its rotation sweeps over the lap and a portion of the surface of the corresponding shelf. The lap 14 rests at its periphery on an upstanding peripher al flange on a circular support plate 120, Fig. 3, which is mounted on a vertical shaft 123 driven through gearing from an electric motor; the lap, which is cast iron, is radially corrugated on both faces and at its upper central portion is engaged by a flange 144 on a nut 142 which can be adjusted on a screwed stud 136 upstanding from the plate 120 to vary the contour of the lap to any degree from its initial slightly convex form.to a slightly concave form. The two plates 170 are suspended by drive spindles 176, Fig. 3, from a superposed box 34 which carries gearing for driving the spindles from the vertical shaft 123; the shaft 123 is, for this purpose, extended upwardly into the box 34 by a shaft 260 which has a pin-and-sleeve connection 262 with the stud 136 and at its upper end drives a variable-speed belt-andpulley connection 84 with a gear train 276, 278 &c. for rotating the spindles 176. The box 34 is supported above the table 12 by two vertically-adjustable posts 70, Figs. 1 and 3, and the two rings 186 surrounding the plates 170 are suspended from the box 34 by rods 188 permitting vertical adjustment of the rings. A hopper H, Fig. 5, associated with each plate 170 is arranged to feed work-pieces down a shoot 28 on to a slotted portion of the shelf 26 where an endless feed belt 31 driven by a motor M3 engages the undersides of the workpieces and impels them through an opening in the ring 186 into successive pockets 172 of the rotating plate 170. Each hopper, the corresponding shelf 26, and belt drive 31 are supported from a block 92, Figs. 1 and 5, which is vertically adjustable on the corresponding side of the table 12 for positioning the members at the desired level in relation to the lap 14. The discharge of the workpiece occurs after the plate 170 has moved them over the shelf 26 and lap 14 through an angle of 300 degrees and takes place when they again reach the shelf through an opening 32 in the latter leading to a shoot 33. If desired, each workpiece when positioned in a pocket 172 may be subjected to downward pressure by a weight 202, Fig. 7, pivotally carried by the free end of a leaf spring 214 projecting radially from the plate 170; the pivotal mounting of the weight enables it to rotate about its vertical axis and so does not prevent the rotation of the workpiece about its axis while it is being lapped, and a screw 224 acts on each spring to determine whether the weight is urged down on the workpiece or merely rests upon it. A cam formation on the upper edge of the ring 186 coacts with the free end of each spring when it reaches the work-feeding opening in the ring so as to lift the weight temporarily and leave the coresponding work pocket clear for the entry of a new workpiece. A ring 22, Fig. 3, for dressing the lap 14 is supported by a spindle 310 from an extension 76 of the box 34 so that it can be adjusted both vertically and radially of the lap; the ring is of greater diameter than the radial width of the annular operative surface of the lap so that, depending upon the radial position of the ring and therefore its degree of overhang in relation to this surface, the lap can be formed concave, flat or convex. Abrasive grit suspended in a liquid is fed from a tank 36, Fig. 1, through a valve-controlled orifice 43 and then along a flexible wire 46 to the ring 22 and lap 14.